Method and apparatus for magnetically treating flowing liquids

ABSTRACT

An apparatus and method is disclosed including first and second housing halves which are welded together to attach the apparatus to a pup joint installed in an oil casing. The housing includes a cylindrical portion and first and second frustoconical portions at opposite axial ends thereof. Axially extending L-shaped spacers are secured to the inside portion and include longitudinal edges which abut with the outer surface of the pipe. Series of axially spaced, first and right parallelepiped shaped magnets are sandwiched between the inside portion of the cylindrical portion and the outer surface of the pipe, with the poles of the first and magnets being reversed relative to the pipe. The housing halves are welded along their longitudinal free edges after being clamped together by a clamping band with sufficient force to secure the apparatus to the pipe generally by frictional forces and being free of the attachment to the pipe.

BACKGROUND

1. Field of the Invention

This invention relates generally to apparatus for magnetically treatinga liquid flowing through a pipe, and pertains more particularly tounpotted apparatus that can be readily held in place against theexterior of the tubing string installed in an oil well casing pipe.

2. Description of the Prior Art

Perhaps U.S. Pat. Nos. 4,367,143; 5,078,870; and 5,198,106 arerepresentative of the state-of-the-art. However, as mentioned in theaforementioned issued patents, U.S. Pat. No. 3,328,878 also isrepresentative of earlier prior art. The disclosures of each of thesepatents mention scale and paraffin problems, pointing out that scale cantake various forms but typical of the substances creating scale problemsare calcium carbonate, calcium sulfate, barium sulfate, sodium chloride,magnesium sulfate, silica, as well as various oils, waxes and greases inaddition to paraffin. Accumulations of these substances on the interiorOf the pipe obviously produce problems, especially as far as causing agreater resistance to liquid flow within the pipe, and also where heatis applied to the pipe's exterior, the collected substances act as anobjectionable thermal insulator. Sufficient accumulations, quiteobviously, require that, the piping system be inactivated and the pipesindividually cleaned out, a time-consuming and costly procedure wherethe system is an industrial one, particularly due to the fact that theparticular piping system is not productive during the shutdown period.

The polarization of diamagnetic materials through the agency ofrelatively strong magnetic fields provided by permanent magnetic meansis generally well understood and need not be repeated at this time,although reference may be made to the patents herein referred to for abasic understanding of what is involved. Very succinctly, however, theprinciple behind the polarization is to prevent the formation ofsufficiently objectionable deposits on the inside of the pipe, themagnetic action causing the diamagnetic materials to move inwardly underthe influence of a sufficiently strong magnetic field.

The difficulty in the past, however, has been with respect to providingsufficiently strong magnetic fields on the tubing string installed in anoil well casing pipe. Such tubing string is prone to incrustation ofparaffin, asphaltine scale/deposits along with salt water and hard waterdeposits. Presently, chemicals are injected into the oil wells toprevent deposits from plugging the tubing string. However, when thismethod fails, the tubing string is removed from the oil well at greatexpense and cleaned out after its removal from the oil well. Attempts totreat the flow through the tubing string to prevent incrustation havenot proven successful. First, the spacing between the tubing string andthe oil well casing pipe is very restrictive and does not allow use ofmagnetic units which are conventionally utilized for exposed pipes.Further, the tubing string is typically formed of Schedule 80 carbonsteel and is tested for 3,000 psi (210 kg/sq. cm) and 175,000 pounds(65,000 kg) of tensile strength, and therefore transmission of magneticflux through the tubing string is relatively difficult. Furthermore,installation of the tubing string is sometimes 17,000 feet (5,000meters) below the surface and is not in a straight line. Thus,considerable force estimated to be in the range of 20,000 pounds (7,500kg) is exerted during installation on the side of the tubing stringand/or upon any accessories mounted thereto.

It is thus an object of the present invention to provide a novelapparatus for magnetically treating liquids flowing through the tubingstring installed in a well casing pipe.

It is further an object of the present invention to provide such a novelmagnetic apparatus which is attached to a pup joint without physicalalteration of the pup joint.

It is further an object of the present invention to provide such a novelmagnetic apparatus which is secured on the pipe solely by frictionalforces.

It is further an object of the present invention to provide such a novelmagnetic apparatus which is able to withstand the rigors of installationthousands of feet (meters) below the surface.

SUMMARY

Surprisingly, these objects and other aims can be satisfied in the fieldof magnetically treating flowing liquids by providing, in the mostpreferred form, a plurality of parallel spacers secured atcircumferentially spaced locations to the inside surface of thecylindrical portion of a housing, with series of axially spaced, firstand second magnets being sandwiched between the inside surface of thecylindrical portion of the housing and the outer surface of the pipe andcircumferentially spaced from each other and from the spacers, with thepoles of the first and second magnets being reversed relative to thepipe.

In a further aspect of the present invention, first and second, radiallyseparable portions of a magnetic apparatus are clamped on a pipe andthen secured together with sufficient force to secure the magneticapparatus to the pipe generally by frictional forces between themagnetic apparatus and the pipe and without attachment of the magneticapparatus to the pipe. In a preferred form, the pipe with the magneticapparatus so secured thereon is inserted within a casing pipe of adiametric size larger than the pipe and the magnetic apparatus securedthereon.

The present invention will become clearer in light of the followingdetailed description of an illustrative embodiment of this inventiondescribed in connection with the drawings.

DESCRIPTION OF THE DRAWINGS

The illustrative embodiment may best be described by reference to theaccompanying drawings where:

FIG. 1 shows an elevational view of a magnetic apparatus secured to apup joint pipe of a well pipe tubing string installed in an oil wellcasing pipe according to the preferred teachings of the presentinvention, with portions exploded therefrom.

FIG. 2 shows a horizontal sectional view of the apparatus of FIG. 1according to section line 2--2 of FIG. 1.

FIG. 3 shows a vertical sectional view of the apparatus of FIG. 1according to section line 3--3 of FIG. 2.

All figures are drawn for ease of explanation of the basic teachings ofthe present invention only; the extensions of the Figures with respectto number, position, relationship, and dimensions of the parts to formthe preferred embodiment will be explained or will be within the skillof the art after the following teachings of the present invention havebeen read and understood. Further, the exact dimensions and dimensionalproportions to conform to specific force, weight, strength, and similarrequirements will likewise be within the skill of the art after thefollowing teachings of the present invention have been read andunderstood.

Where used in the various figures of the drawings, the same numeralsdesignate the same or similar parts. Furthermore, when the terms"first", "second", "inside", "outside", "outer", "inner", "upper","lower", "height", "width", "length", "end", "side", "horizontal","vertical", "longitudinal", "axial", "circumferential", "radial", andsimilar terms are used herein, it should be understood that these termshave reference only to the structure shown in the drawings as it wouldappear to a person viewing the drawings and are utilized only tofacilitate describing the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As can be seen in the Figures, a pipe indicated by the reference numeral10 has been shown. Pipe 10 may be formed of carbon steel andspecifically in the most preferred form is a pup joint certified by theAmerican Petroleum Institute for installation in an oil well casing pipe12, pipe 10 having been hatched for metal. Also, pipe 10, in practice,may vary considerably in diameter depending upon the diameter of casingpipe 12. The manner in which various pipe diameters are accommodatedwill become clear as the description progresses.

In juxtaposition with pipe 10 is apparatus denoted generally by thereference numeral 14. Apparatus 14 includes a housing 16 including acylindrical portion 18 and first and second frustoconical portions 20located on opposite axial sides of and partially closing cylindricalportion 18. In the most preferred form, cylindrical portion 18 hasinside and outside surfaces having circular cross sections of diametersslightly larger than the diameter of the circular cross section of theouter surface of pipe 10. In the most preferred form, the inside surfaceof portion 18 has a diameter in the order of 1 inch (2.54 cm) largerthan the outer surface of pipe 10. Portion 18 has an elongated length inthe order of 7-9 inches (18-23 cm). Portions 20 each includes a majorbase having inside and outside surfaces having circular cross sectionsof diameters equal to and interconnected to the diameters of the insideand outside surfaces of an axial end of portion 18. Portions 20 eachinclude a minor base having an inside surface having a circular crosssection of a diameter generally equal and corresponding to the outersurface of pipe 10. In the most preferred form, housing 16 is dividedinto first and second longitudinal portions 16a and 16b which areradially separable from each other and pipe 10, with portions 16a and16b being halves in the most preferred form which are mirror images ofeach other and preferably are of identical construction.

Housing 16 further includes a plurality of parallel spacers 22 forholding cylindrical portion 18 generally concentric to pipe 10.Specifically, in the most preferred form, spacers 22 are elongated angleirons including a first leg 24 secured to the inside surface ofcylindrical portion 18 at circumferentially spaced locations such as bywelding and a second leg 26 extending perpendicularly from leg 24 andhaving a free edge for abutting with pipe 10. The free edges of spacers22 terminate in a cylinder having a diameter generally equal to thediameter of the outer surface of pipe 10. Spacers 22 have an axiallength generally equal to and coextensive with the axial length ofcylindrical portion 18. Spacers 22 are circumferentially spaced aroundpipe 10 and extend generally parallel to the axis of pipe 10 and ofcylindrical portion 18. In the preferred form, each housing half 16a and16b includes first and second edge spacers 22 located adjacent to thelongitudinal edges thereof, with the free edges of legs 24 being locatedcircumferentially outward of legs 26. Furthermore, each housing half 16aand 16b further includes at least one intermediate spacer 22 locatedintermediate the first and second edge spacers 22 and the longitudinaledges of halves 16a and 16b. The number of intermediate spacers 22depends upon the diameter of pipe 10 and cylindrical portion 18, withthree spacers 22 shown in the drawings for each housing half 16a and 16bfor pipe 10 having a diameter of 25/8 inches (62/3 cm).

Apparatus 14 further includes a first series of permanent magnets 28located at equally spaced circumferential intervals intermediate pipe 10and cylindrical portion 18 with magnets 28 being arranged having theirsouth poles located radially inwardly and adjacent pipe 10 and havingtheir north poles located radially outwardly and adjacent cylindricalportion 18. Apparatus 14 further includes a second series of permanentmagnets 30 located at equally spaced circumferential intervalsintermediate pipe 10 and cylindrical portion 18 with magnets 30 beingarranged having their north poles located radially inwardly and adjacentpipe 10 and having their south poles located radially outwardly andadjacent cylindrical portion 18. Magnets 30 are longitudinally spacedalong pipe 10 and cylindrical portion 18 from magnets 28. The number andlongitudinal positioning of magnets 30 correspond to the number andlongitudinal position of magnets 28. The number of magnets 28 and 30 ineach series depends upon the diameter of pipe 10 and cylindrical portion18, with two magnets 28 and 30 shown in the drawings for each half 16aand 16b positioned intermediate the edge spacers 22 and the intermediatespacer 22 for pipe 10 having a diameter of 25/8 inches (62/3 cm).Magnets 28 and 30 in the preferred form are formed of neodymium materialin the shape of a right parallelepiped having a height of 3/4 inch (1.9cm) along the longitudinal direction, i.e. the distance between the topand bottom edges of magnets 28 and 30, a width of 1/2 inch (1.27 cm)along a radial direction, i.e. the distance between the inner and outeredges of magnets 28 and 30, and a thickness of 1/4 inch (0.64 cm) alonga circumferential direction with reference to pipe 10 and cylindricalportion 18, i.e. the distance between the first and second faces ofmagnets 28 and 30. It can then be appreciated that the height of magnets28 and 30 is generally equal to but larger than the width and that thewidth is substantially greater and in the most preferred form double thethickness of magnets 28 and 30.

Now that the basic construction of apparatus 14 according to thepreferred teachings of the present invention has been explained, themanner of installation of apparatus 14 to pipe 10 and of pipe 10including apparatus 14 within casing pipe 12 can be set forth.Specifically, housing halves 16a and 16b including spacers 22 can befabricated for the particular diameter of pipe 10 to be utilized. Thedesired number of magnets 28 and 30 corresponding to the particulardiameter of pipe 10 can then be magnetically attached at the appropriatecircumferential spacing around pipe 10, with magnets 28 and 30 beinglongitudinally spaced along pipe 10. At that time, housing halves 16aand 16b can be positioned on pipe 10 with magnets 28 and 30 positionedcircumferentially spaced from spacers 22 and with their longitudinalfree edges abutting. At that time, a clamping band 32 can be positionedaround cylindrical portion 18 of housing 16 and tightened to tightlyclamp housing halves 16a and 16b together with sufficient force tosecure apparatus 14 to pipe 10 generally by frictional forces betweenapparatus 14 and pipe 10. At that time, housing halves 16a and 16b canbe secured together such as by welding 34 the longitudinal free edges ofhalves 16a and 16b together. Alternately, plates can be welded to eachfrustoconical portion 20 overlapping the longitudinal free edgesthereof, with the plates not exceeding the diameter of cylindricalportion 18. It can then be appreciated that magnets 28 and 30 aretightly sandwiched between the inside surface of cylindrical portion 18and the outer surface of pipe 10. Further, it can be appreciated thatfrustoconical portions 20 close the spacing between the inside surfaceof cylindrical portion 18 and the outer surface of pipe 10 on theopposite axial ends of cylindrical portion 18.

In the most preferred form, apparatus 14 is not in any way welded orotherwise secured to pipe 10 in a manner which would affect the physicalcharacteristics thereof and specifically which would affect thecertification of pipe 10. However, apparatus 14 is very rigidly securedto pipe 10 according to the preferred teachings of the presentinvention. Specifically, removal of apparatus 14 in a radial directionis prevented due to the securement of halves 16a and 16b together andconcentrically around pipe 10. Sliding of apparatus 14 in a longitudinaldirection is prevented due to the abutment and clamping of the minorbase of portions 20 and of the free edges of legs 26 of spacers 22against the outer surface of pipe 10. Additionally, the sandwiching ofmagnets 28 and 30 between cylindrical portion 18 and pipe 10 alsoassists in the securement of apparatus 14 to pipe 10. Thus, according tothe teachings of the present invention, a standard, previously certifiedpipe 10 can be purchased, with apparatus 14, according to the preferredteachings of the present invention, being added thereto withoutrequiring pipe 10 to be retested or certified prior to installation.

Pipes 10 with apparatus 14 secured thereto, according to the preferredteachings of the present invention, can then be transported to the oilwell. The well pipe tubing can then be installed in casing pipe 12 inthe usual manner and including pipe 10 and apparatus 14 secured theretoat approximately 1,000 feet (300 meters) intervals along the well pipetubing. It should be appreciated that due to the very tight manner thatapparatus 14 grips pipe 10 and the reinforcement provided to apparatus14 by spacers 22, apparatus 14 is able to withstand the rigors ofinstallation in casing pipe 12 without dislodgment from or along pipe10.

After installation of the well pipe tubing including apparatus 14 ataxial spaced intervals, apparatus 14 magnetically treats the flowthrough the well pipe tubing to prevent and/or eliminate incrustationinside of the well pipe tubing and thus saving maintenance costs andmaximizing flow through the well pipe tubing and thus the productionfrom the oil well.

I claim:
 1. Apparatus for magnetically treating flowing liquids througha pipe, with the pipe having an outer surface having a circular crosssection of a diameter, comprising, in combination: a housing including acylindrical portion, with the cylindrical portion having inside andoutside surfaces having circular cross sections of diameters larger thanthe diameter of the outer surface of the pipe, with the housing furtherincluding a plurality of parallel spacers secured at circumferentiallyspaced locations to the inside surface of the cylindrical portion andhaving axial lengths generally equal to the axial length of thecylindrical portion, with the spacers having free edges which terminatein a cylinder having a diameter generally equal to the diameter of theouter surface of the pipe; and means for producing a magnetic field fora liquid flowing through the pipe comprising, in combination: a seriesof first magnets sandwiched between the inside surface of thecylindrical portion and the outer surface of the pipe, with the firstmagnets being circumferentially spaced from each other and from thespacers; and a series of second magnets sandwiched between the insidesurface of the cylindrical portion and the outer surface of the pipe andaxially spaced from the first magnets, with the second magnets beingcircumferentially spaced from each other and from the spacers, with thefirst and second magnets each having north and south poles, with thefirst magnets having the north poles located radially outward of thesouth poles and the second magnets having the south poles locatedradially outward of the north poles.
 2. The apparatus of claim 1 whereinthe housing is secured to the pipe generally by frictional forcesbetween the free edges of the spacers and the outer surface of the pipeand free of any attachment to the pipe.
 3. The apparatus of claim 1wherein the spacers are L-shaped having first legs secured to the insidesurface of the cylindrical portion and having second legs integrallyextending generally perpendicular to the first legs and terminating inthe free edges.
 4. The apparatus of claim 1 wherein the magnets have aright parallelepiped shape having a top edge, a bottom edge, an inneredge abutting with the outer surface of the pipe, an outer edge abuttingwith the inside surface of the cylindrical portion, a first face, and asecond face, with the height of the inner and outer edges between thetop edge and the bottom edge being generally equal to the width of thefirst and second faces between the inner and outer edges and being amultiple of the thickness of the top and bottom edges between the firstand second faces, with the poles located at the inner and outer edges.5. The apparatus of claim 4 wherein the width of the first and secondfaces between the inner and outer edges is double the thickness of thetop and bottom edges between the first and second faces.
 6. Theapparatus of claim 5 wherein the height of the inner and outer edgesbetween the top edge and the bottom edge is larger than the thickness ofthe top and bottom edges between the first and second faces.
 7. Theapparatus of claim 1 wherein the housing further includes first andsecond means for closing the spacing between the inside surface of thecylindrical portion and the outer surface of the pipe on the oppositeaxial ends of the cylindrical portion.
 8. The apparatus of claim 7wherein the closing means each comprise a frustoconical portion, withthe frustoconical portions each including a major base having inside andoutside surfaces having circular cross sections of diameters equal toand interconnected to the diameters of the inside and outside surfacesof the cylindrical portion, with the frustoconical portions eachincluding a minor base located axially outward of the cylindricalportion and having an inside surface having a circular cross section ofa diameter generally equal to the pipe.
 9. The apparatus of claim 1wherein the housing is divided into first and second longitudinalportions which are radially separable from the pipe, with each of thelongitudinal portions including first and second longitudinal edges;wherein the housing includes means for securing the first and secondlongitudinal portions together with the longitudinal edges of the firstlongitudinal portion abutting with the longitudinal edges of the secondlongitudinal portion and with the first and second longitudinal portionsbeing secured together generally without exceeding the diameter of theoutside surface of the cylindrical portion and being free of anyattachment to the pipe.
 10. The apparatus of claim 9 wherein eachhousing portion includes first and second edge spacers located adjacentto the first and second longitudinal edges and at least a firstintermediate spacer located intermediate the first and second edgespacers.
 11. The apparatus of claim 9 wherein the housing is secured tothe pipe generally by frictional forces between the free edges of thespacers and the outer surface of the pipe.
 12. Method for magneticallytreating flowing liquids comprising the steps of: providing a pipeincluding an outer surface having a circular cross section of adiameter; providing a magnetic apparatus producing a magnetic field andincluding a housing having a cylindrical portion, with the cylindricalportion including an outside surface having generally circular crosssections of a diameter larger than the diameter of the pipe, with theoutside surface of the cylindrical portion of the housing having aradial size larger than the remaining portions of the housing, with themagnetic apparatus including the housing being divided into first andsecond longitudinal portions which are radially separable from the pipe;attaching the first and second longitudinal portions together to securethe magnetic apparatus to the pipe generally by frictional forcesbetween the first and second longitudinal portions and the pipe andbeing free of attachment of the first and second longitudinal portionsto the pipe; and flowing the liquid through the pipe after the magneticapparatus is secured to the pipe characterized in that the attachingstep comprises the steps of: clamping the first and second longitudinalportions on the pipe with sufficient force to secure the magneticapparatus to the pipe generally by frictional forces between the firstand second longitudinal portions and the pipe; attaching the first andsecond longitudinal portions together generally without exceeding thediameter of the cylindrical portion; and removing the clamping forcefrom the first and second longitudinal portions after the first andsecond longitudinal portions are attached together.
 13. The method ofclaim 12 further comprising the step of inserting the pipe with themagnetic apparatus secured thereon within a casing pipe, with the pipeand the magnetic apparatus secured thereon having a diametric size lessthan the casing pipe.
 14. The method of claim 13 wherein the clampingstep comprises the step of tightening a band around the outside surfaceof the cylindrical portion.
 15. The method of claim 14 wherein the stepof providing the magnetic apparatus comprises the step of providing themagnetic apparatus including the housing having the cylindrical portionincluding an inside surface having circular cross sections of a diameterlarger than the diameter of the outer surface of the pipe, with thehousing further including a plurality of parallel spacers secured atcircumferentially spaced locations to the inside surface of thecylindrical portion and having axial lengths generally equal to theaxial length of the cylindrical portion, with the spacers having freeedges which terminate in a cylinder having a diameter generally equal tothe diameter of the outer surface of the pipe.
 16. The method of anyclaim 14 wherein the step of providing the magnetic apparatus comprisesthe step of providing the housing further including first and secondfrustoconical portions, with the cylindrical portion including an insidesurface having circular cross sections of a diameter larger than thediameter of the outer surface of the pipe, with the frustoconicalportions each including a major base having inside and outside surfaceshaving circular cross sections of diameters equal to and interconnectedto the diameters of the inside and outside surfaces of the cylindricalportion, with the frustoconical portions each including a minor baselocated axially outward of the cylindrical portion and having an insidesurface having a circular cross section of a diameter generally equal tothe pipe.
 17. The method of any claim 12 wherein the step of providingthe magnetic apparatus comprises the step of providing the first andsecond longitudinal portions each including first and secondlongitudinal edges having an outer radial size not exceeding the outsidesurface of the cylindrical portion; and wherein the clamping stepincludes abutting the longitudinal edges of the first longitudinalportion with the longitudinal edges of the second longitudinal portion.18. The method of claim 17 wherein the attaching step comprises thesteps of welding the first longitudinal edges of the first and secondlongitudinal portions together and welding the second longitudinal edgesof the first and second longitudinal portions together.
 19. The methodof claim 12 wherein the clamping step comprises the step of tightening aband around the outside surface of the magnetic apparatus.
 20. Methodfor magnetically treating flowing liquids comprising the steps of:providing a pipe including an outer surface having a circular crosssection of a diameter; providing a magnetic apparatus producing amagnetic field and including a housing having a cylindrical portion,with the magnetic apparatus including the housing being divided intofirst and second longitudinal portions which are radially separable fromthe pipe; attaching the first and second longitudinal portions togetherand being free of attachment of the first and second longitudinalportions to the pipe, with the magnetic apparatus being secured withsufficient force to the pipe generally by frictional forces between thefirst and second longitudinal portions and the pipe, with thecylindrical portion having inside and outside surfaces having circularcross sections of diameters larger than the diameter of the outersurface of the pipe, with the magnetic apparatus further including aseries of first magnets sandwiched between the inside surface of thecylindrical portion and the outer surface of the pipe, with the firstmagnets being circumferentially spaced from each other, with themagnetic apparatus further including a series of second magnetssandwiched between the inside surface of the cylindrical portion and theouter surface of the pipe and axially spaced from the first magnets,with the second magnets being circumferentially spaced from each other,with the first and second magnets each having north and south poles,with the first magnets having the north poles located radially outwardof the south poles end the second magnets having the south poles locatedradially outward of the north poles, with the magnetic apparatus furtherincluding a plurality of parallel spacers secured at circumferentiallyspaced locations to the inside surface of the cylindrical portion andhaving axial lengths generally equal to the axial length of thecylindrical portion, with the spacers having free edges which terminatein a cylinder having a diameter generally equal to the diameter of theouter surface of the pipe, with the first and second magnets beingcircumferentially spaced from the spacers; and flowing the liquidthrough the pipe after the clamping force is removed.
 21. The method ofclaim 20 wherein the step of providing the magnetic apparatus comprisesthe step of providing the magnets of a right parallelepiped shape andhaving a top edge, a bottom edge, an inner edge abutting with the outersurface of the pipe, an outer edge abutting with the inside surface ofthe cylindrical portion, a first face, and a second face, with theheight of the inner and outer edges between the top edge and the bottomedge being generally equal to the width of the first and second facesbetween the inner and outer edges and being a multiple of the thicknessof the top and bottom edges between the first and second faces, with thepoles located at the inner and outer edges.
 22. Method for magneticallytreating flowing liquids comprising the steps of: providing a pipeincluding an outer surface having a circular cross section of adiameter; providing a magnetic apparatus producing a magnetic field andincluding a housing having a cylindrical portion, with the magneticapparatus including the housing being divided into first and secondlongitudinal portions which are radially separable from the pipe; andattaching the first and second longitudinal portions together and beingfree of attachment of the first and second longitudinal portions to thepipe, with the cylindrical portion having inside and outside surfaceshaving circular cross sections of diameters larger than the diameter ofthe outer surface of the pipe, with the housing further including aplurality of parallel spacers secured at circumferentially spacedlocations to the inside surface of the cylindrical portion and havingaxial lengths generally equal to the axial length of the cylindricalportion, with the spacers having free edges which terminate in acylinder having a diameter generally equal to the diameter of the outersurface of the pipe, with the spacers being of an L-shape includingfirst legs secured to the inside surface of the cylindrical portion andhaving second legs integrally extending generally perpendicular to thefirst legs and terminating in the free edges; and flowing the liquidthrough the pipe after the clamping force is removed.
 23. Apparatus formagnetically treating flowing liquids through a pipe, with the pipehaving an outer surface having a circular cross section of a diameter,comprising, in combination: a housing including a cylindrical portion,with the cylindrical portion having inside and outside surfaces havingcircular cross sections of diameters larger than the diameter of theouter surface of the pipe, with the housing further including aplurality of parallel spacers secured at circumferentially spacedlocations to the inside surface of the cylindrical portion and havingaxial lengths generally equal to the axial length of the cylindricalportion, with the spacers having free edges which terminate in acylinder having a diameter generally equal to the diameter of the outersurface of the pipe; and means located between the inside surface of thecylindrical portion and the outer surface of the pipe for producing amagnetic field for a liquid flowing through the pipe, with the spacersbeing L-shaped and having first legs secured to the inside surface ofthe cylindrical portion and having second legs integrally extendinggenerally perpendicular to the first legs and terminating in the freeedges.